A fibre optic acoustic emission sensor with inherent drift compensation

摘要

The chirped Bragg grating technique have opened up new ways to measure transient strain events such as acoustic waves without encountering problems concerning the large dynamic range. Theoretical analysis shows that by using the "Chirped Grating Interferometer", GGI, concept with global strain and temperature compensation the sensor would mechanically maintain full sensitivity over global strain and temperature variations. A sensor that discriminates against global strain and temperature variations could be adapted to the acoustic wavelength the two chirped gratings of the sensor will experience strain amplitudes of different sign and effectively enlarge the path imbalance of the sensor. Initial calculations for the acoustic application indicate that PZT-performance of even better is within reach.